(CN) – For the last 4,000 years, termites in northeastern Brazil have been busy building their home: 200 million cone-shaped mounds that can be seen from space.
“This is apparently the world’s most extensive bioengineering effort by a single insect species,” said Roy Funch of Universidade Estadual de Feira de Santana in Brazil. “Perhaps most exciting of all, the mounds are extremely old – up to 4,000 years, similar to the ages of the pyramids.”
Researchers say active termites over the course of thousands of years deposited soil in approximately 200 million cone-shaped mounds, each measuring about 2.5 meters tall and 9 meters across. This vast array of regularly spaced mounds covers an area the size of Great Britain and are the result of slow and steady excavation of a network of interconnected underground tunnels.
“These mounds were formed by a single termite species that excavated a massive network of tunnels to allow them to access dead leaves to eat safely and directly from the forest floor,” University of Salford researcher Stephen Martin said.
“The amount of soil excavated is over 10 cubic kilometers, equivalent to 4,000 great pyramids of Giza, and represents one of the biggest structures built by a single insect species,” Martin added.
The mounds are largely hidden from view in the fully deciduous, semiarid, thorny-scrub caatinga forests unique to northeastern Brazil. Scientists discovered the mounds after some of the land was cleared for pasture in recent decades.
Researchers hypothesized that the strangely regular spatial pattern of the mounds could be driven by competition amongst termites in neighboring mounds. Behavioral tests proved otherwise, finding little aggression at the mound level compared to obvious aggression among termites collected at greater distances from one another.
The findings led Martin and his colleagues to propose that the mound pattern came about through self-organizational processes facilitated by the increased connectivity of the tunnel network, driven by episodic leaf-fall in the dry forest.
They say that a pheromone map might allow the termites to minimize their travel time from any location in the colony to the nearest waste mound. The vast tunnel network apparently allows safe access to a sporadic food supply, similar to what’s been seen in naked mole-rats, which also live in arid regions and construct very extensive burrow networks to obtain food.
“It’s incredible that, in this day and age, you can find an ‘unknown’ biological wonder of this sheer size and age still existing, with the occupants still present,” Martin said.
Scientists say there are many questions to be answered. For instance, no one knows how these termite colonies are physically structured because a queen chamber of the species has yet to be found.
Researchers collected soil samples from the centers of 11 mounds and were able to pinpoint the termite activity between 690 to 3,820 years ago, making them about as old as the world’s oldest known termite mounds in Africa.
The findings were published Monday in the journal Current Biology.